Marine main engine waste heat recovery system and method

Abstract

The invention discloses a marine main engine waste heat recovery system and method.The marine main engine waste heat recovery system comprises a hot water circulation system, a fuel oil hot water heating system and a heat storage system, and the hot water circulation system comprises a plurality of cylinder sleeve water heat exchangers used for circulating water heat exchange; an outlet of each cylinder sleeve water heat exchanger is connected with an inlet of a cylinder sleeve water heat supply water collector through a pipeline, an outlet of the cylinder sleeve water heat supply water collector is connected with an inlet of a heat supply distributor through a pipeline, an outlet of the heat supply distributor is connected to each user through each pipeline, and each user is connected with an inlet of a heat supply collector through a pipeline. An outlet of the heat supply recycling device is connected with an inlet of the hot water circulating pump set through a pipeline, an outlet of the hot water circulating pump set is connected with an inlet of the heat source water return device through a pipeline, and an outlet of the heat source water return device is connected with inlets of the cylinder sleeve water heat exchangers through pipelines. The waste heat of the main machine can be effectively utilized, operation is easy, and universality is high; the comprehensive utilization efficiency of heat energy is improved, and the operation cost of the ship is effectively reduced.

Description

Technical Field

[0001] This invention relates to a waste heat recovery system and method for ship main engines, and more particularly to a waste heat recovery system and method for ship main engines that can meet different needs under all weather and all operating conditions, belonging to the field of ship technology. Background Technology

[0002] In 2021, the IMO revised the International Convention for the Prevention of Pollution from Ships (MARPOL), introducing a more stringent Carbon Intensity Index (CII) for ship operations. This index will affect the inspection and implementation of the Ship Energy Efficiency Management Program (SEEMP). A significant amount of waste heat generated during ship operations remains unused, wasting energy and potentially causing environmental pollution.

[0003] Different tonnage ships are equipped with different numbers of diesel engines, and the number of diesel engines used during navigation varies depending on the working conditions. At the same time, different climates and waters cause the waste heat recovery schemes of ships to vary, making them non-universal and difficult to standardize. Furthermore, the system functions of existing technical solutions cannot be selected according to the specific working conditions during navigation, and cannot achieve optimal waste heat recovery and utilization. Summary of the Invention

[0004] The technical problem to be solved by this invention is: how to optimize the recovery and utilization of waste heat from ships.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is to provide a waste heat recovery system for marine main engines, characterized in that it includes a hot water circulation system, a fuel oil hot water heating system, and a heat storage system. The hot water circulation system includes multiple cylinder-lined water heat exchangers for circulating water heat exchange. The outlet of each cylinder-lined water heat exchanger is connected to the inlet of the cylinder-lined water heating collector via a pipeline. The outlet of the cylinder-lined water heating collector is connected to the inlet of the heating distributor via a pipeline. The outlet of the heating distributor is connected to each user via various pipelines. Each user is connected to the inlet of the heating return collector via a pipeline. The outlet of the heating return collector is connected to the inlet of the hot water circulation pump group via a pipeline. The outlet of the hot water circulation pump group is connected to the inlet of the heat source return water device via a pipeline. The outlet of the heat source return water device is connected to the inlet of each cylinder-lined water heat exchanger via a pipeline. The fuel-fired hot water heating system includes a fuel-fired hot water heating device. The outlet of the cylinder liner water heating collector is connected to the inlet of the fuel-fired hot water heating device via a pipeline, and the outlet of the fuel-fired hot water heating device is connected to the inlet of the heating distributor via a pipeline. The heat storage system includes a phase change accumulator. The outlet of the cylinder liner water heating collector is connected to the inlet of the phase change accumulator via a pipeline. The outlet of the phase change accumulator is connected to the inlet of the heat return collector, the inlet of the fuel oil hot water heating device, and the inlet of the heat distributor via pipelines. The outlet of the heat return collector is connected to the inlet of the phase change accumulator via a pipeline equipped with a hot water circulation pump for the heat storage system. Each pipeline is equipped with a valve.

[0006] Preferably, the outlet of the cylinder liner water heating collector is divided into two paths: one path leads to the fuel-fired hot water heating device and the heating distributor, and the other path leads to the inlet of the phase change accumulator. A first temperature control valve is provided on the path leading to the fuel-fired hot water heating device and the heating distributor. After passing through the first temperature control valve, it is divided into two paths: one path leads to the inlet of the fuel-fired hot water heating device, and the other path leads to the inlet of the heating distributor.

[0007] Preferably, the outlet of the heat source return water device is divided into two types: one type is connected to the inlet of the cylinder liner water heating collector through a pipeline, and the other type is provided with a second temperature control valve on each pipeline leading to the cylinder liner water heat exchanger, and after passing through the second temperature control valve, it is divided into two paths, one path leading to the inlet of the cylinder liner water heat exchanger and the other path leading to the inlet of the cylinder liner water heating return water collector.

[0008] Preferably, the hot water circulation pump set includes three pumps connected in parallel, two of which are in use and one is a standby pump. Each pump is equipped with a valve on its pipeline. The inlet and outlet ends of the hot water circulation pump set are equipped with a bypass pipeline with a valve.

[0009] Preferably, the phase change heat storage outlet is divided into two paths: one path leads to the fuel oil hot water heating device and the heat distribution unit, and the other path leads to the heat collection unit. A third temperature control valve is provided on the path leading to the fuel oil hot water heating device and the heat distribution unit. After passing through the third temperature control valve, it is divided into two paths: one path leads to the inlet of the fuel oil hot water heating device, and the other path leads to the inlet of the heat distribution unit.

[0010] Preferably, the users include heated chambers, seawater desalination plants, heated electric / hot water tanks, and heat transfer water containers for heated air conditioning systems.

[0011] A method for recovering waste heat from a ship's main engine, characterized by the use of a waste heat recovery system for the main engine, comprising the following steps when the ship is in winter or in a cold region: Circulating water first undergoes heat exchange in a cylinder liner water heat exchanger, and after heat exchange, enters a cylinder liner water heating collector and then a first temperature control valve for temperature measurement. If the circulating water temperature reaches the design temperature of the first temperature control valve, the circulating water flows to and enters a heating distributor; if the circulating water temperature does not reach the design temperature of the first temperature control valve, the circulating water flows to and enters a fuel oil hot water heating device. When the circulating water is heated by the fuel oil hot water heating device to… After the temperature exceeds the maximum design temperature of the first thermostatic valve, the circulating water enters the heating distributor through the pipeline from the outlet of the fuel-fired hot water heating device. The heating distributor distributes the circulating water to each user. After the heat is absorbed, the water returns from each user to the heating collector and then enters the hot water circulation pump group. After being pressurized by the pump of the hot water circulation pump group, it enters the heat source return water device. After exiting the heat source return water device, it flows to the second thermostatic valve corresponding to each cylinder liner water heat exchanger. If the circulating water temperature still reaches the design temperature of the second thermostatic valve, it bypasses the cylinder liner water heat exchanger and directly enters the cylinder liner water heating collector, completing one cycle.

[0012] Preferably, when it is summer or the ship is in a hot region, the users do not need heating and use the phase change heat storage device to store heat. The circulation process is as follows: the circulating water first exchanges heat in the cylinder liner water heat exchanger. After the heat exchange is completed, it enters the cylinder liner water heating collector and then enters the phase change heat storage device. After the heat is absorbed, the circulating water goes to the heating return collector and then enters the hot water circulation pump group. After being pressurized by the pump, it enters the heat source return water device. After exiting the heat source return water device, the flow direction is controlled by the second temperature control valve. If the circulating water temperature still reaches the design temperature of the second temperature control valve, it will directly enter the cylinder liner water heating return collector without passing through the cylinder liner water heat exchanger, thus completing one cycle.

[0013] Preferably, when the ship's main engine is shut down, and the cylinder liner water heat exchanger is not used or only one cylinder liner water heat exchanger is used, the heat of the circulating water is insufficient. The heat in the phase change accumulator is then used. The circulation process is as follows: the circulating water in the phase change accumulator is controlled by a third temperature control valve. If the design temperature of the third temperature control valve is reached, it enters the heating distributor; if the design temperature of the third temperature control valve is not reached, it enters the fuel oil hot water heating device. When the circulating water is heated by the fuel oil hot water heating device to a temperature greater than the maximum design temperature of the third temperature control valve, it enters the heating distributor. The circulating water is distributed from the heating distributor to each user. After the heat is absorbed, the water returns from each user to the heating return collector, and then returns to the phase change accumulator through the hot water circulation pump of the heat storage system, completing one cycle.

[0014] Preferably, the circulating water temperature at the first temperature control valve position is designed to be 85~88℃; the circulating water temperature at the second temperature control valve position is designed to be 65~68℃; and the circulating water temperature at the third temperature control valve position is designed to be 85~88℃.

[0015] Compared with the prior art, the present invention has the following significant advantages: This invention can effectively utilize the waste heat of the main engine, reduce energy waste and negative impacts on the aquatic ecological environment; according to the specific needs of the ship's operation, heat energy can be directly distributed to each user or stored by opening and closing valves. It is simple to operate and highly versatile; it improves the comprehensive utilization efficiency of heat energy and effectively reduces the operating cost of the ship.

[0016] This invention meets all-weather, all-condition requirements by utilizing a heat exchanger to recover waste heat from the ship's main engine. This waste heat is then used to heat cabins, seawater desalination facilities, electric / hot water tanks, and the heat transfer fluid in the air conditioning system. Furthermore, it can be recovered through a heat storage device. The system's valve on / off states can be adjusted according to different operating conditions and weather conditions based on the ship's operational needs. By recovering and utilizing waste heat from the ship's main engine, energy conservation and emission reduction are achieved. Moreover, the recovery system can be rationally selected based on the specific needs of ship operation, thereby reducing the ship's operating costs. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a waste heat recovery system for a ship's main engine.

[0018] Labeling Explanation: 1. Cylinder liner water heat exchanger No. 1; 2. Cylinder liner water heat exchanger No. 2; 3. Cylinder liner water heat exchanger No. 3; 4. Cylinder liner water heat exchanger No. 4; 5. Hot water circulation pump set; 6. Fuel oil hot water heating device; 7. Phase change accumulator; 8. Heating distributor; 9. Heating return collector; 10. Heat source return water device; 11. Cylinder liner water heating water collector; 12. Hot water circulation pump for heat storage system. Detailed Implementation

[0019] To make the present invention more apparent and understandable, preferred embodiments are described in detail below with reference to the accompanying drawings.

[0020] This invention provides a waste heat recovery system for ship main engines, such as... Figure 1 As shown, it includes a hot water circulation system, a fuel oil hot water heating system, and a heat storage system.

[0021] The hot circulating water system is used to exchange heat with the cylinder liner water coming out of the cylinder liner water heat exchanger and recover heat, and use the heat to heat the cabin, seawater desalination, electric / hot water tank and heat the heat transfer medium water of the air conditioning system; the fuel oil hot water heating system and the heat storage system are both placed after the cylinder liner water heating collector 11.

[0022] The hot water circulation system comprises multiple cylinder liner water heat exchangers, a hot water circulation pump set 5, a heating distributor 8, a heating return collector 9, a heat source return water device 10, a cylinder liner water heating collector 11, and corresponding pipelines and valve assemblies. The heating distributor 8 distributes circulating water to each user; the heating return collector 9 collects circulating water from each user; the heat source return water device 10 distributes the circulating water after pumping to each cylinder liner water heat exchanger; and the cylinder liner water heating collector 11 collects the circulating water after heat exchange with the main engine cylinder liner water and then delivers it to the fuel oil hot water heating device 6 or the heating distributor 8. There are four cylinder liner water heat exchangers (Cylinder liner water heat exchanger 1, Cylinder liner water heat exchanger 2, Cylinder liner water heat exchanger 3, and Cylinder liner water heat exchanger 4), each with the same heat exchange capacity.

[0023] The fuel-fired hot water heating system includes a fuel-fired hot water heating device 6, fuel supply pipelines, a temperature control valve, and corresponding valves and pipelines. The heat storage system includes a phase change heat storage device 7, a temperature control valve, and corresponding valves and pipelines. The phase change heat storage device 7 is made of hydrated salt (sodium acetate trihydrate).

[0024] The outlet of each cylinder liner water heat exchanger is connected to the inlet of cylinder liner water heating collector 11 via a pipeline. The outlet of cylinder liner water heating collector 11 is connected to the inlet of heating distributor 8 via a pipeline. The outlet of heating distributor 8 is connected to each user via various pipelines. Each user is connected to the inlet of heating return collector 9 via a pipeline. The outlet of heating return collector 9 is connected to the inlet of hot water circulation pump set 5 via a pipeline. The outlet of hot water circulation pump set 5 is connected to the inlet of heat source return water device 10 via a pipeline. The outlet of heat source return water device 10 is connected to the inlet of each cylinder liner water heat exchanger via a pipeline. The outlet of the cylinder liner water heating collector 11 is connected to the inlet of the fuel oil hot water heating device 6 via a pipeline. The outlet of the fuel oil hot water heating device 6 is connected to the inlet of the heating distributor 8 via a pipeline. The outlet of the cylinder liner water heating collector 11 is connected to the inlet of the phase change accumulator 7 via a pipeline. The outlet of the phase change accumulator 7 is connected to the inlet of the heating return collector 9, the inlet of the fuel oil hot water heating device 6, and the inlet of the heating distributor 8 via pipelines. The outlet of the heating return collector 9 is connected to the inlet of the phase change accumulator 7 via a pipeline equipped with a hot water circulation pump 12 for the heat storage system. Each pipeline is equipped with a valve.

[0025] The outlet of the cylinder liner water heating collector 11 is divided into two paths. One path leads to the fuel oil hot water heating device 6 and the heating distributor 8, and the other path leads to the inlet of the phase change heat accumulator 7. The path leading to the fuel oil hot water heating device 6 and the heating distributor 8 is equipped with a first temperature control valve. After passing through the first temperature control valve, it is divided into two paths. One path leads to the inlet of the fuel oil hot water heating device 6, and the other path leads to the inlet of the heating distributor 8.

[0026] The outlet of the heat source return water device 10 is divided into two types. One type is connected to the inlet of the cylinder liner water heating collector 11 through a pipeline. The other type has a second temperature control valve installed on each pipeline leading to the cylinder liner water heat exchanger. After passing through the second temperature control valve, the pipeline is divided into two paths: one path leads to the inlet of the cylinder liner water heat exchanger, and the other path leads to the inlet of the cylinder liner water heating collector 11.

[0027] The outlet of the phase change heat accumulator 7 is divided into two paths. One path leads to the fuel oil hot water heating device 6 and the heat distribution device 8, and the other path leads to the heat collection device 9. A third temperature control valve is installed on the path leading to the fuel oil hot water heating device 6 and the heat distribution device 8. After passing through the third temperature control valve, it is divided into two paths. One path leads to the inlet of the fuel oil hot water heating device 6, and the other path leads to the inlet of the heat distribution device 8.

[0028] The hot water circulation pump set 5 includes three pumps connected in parallel, two for operation and one for standby. Each pump's pipeline is equipped with a valve. The inlet and outlet ends of the hot water circulation pump set 5 are connected to a bypass pipeline with a valve. Users include heated compartments, seawater desalination plants, heated electric / hot water tanks, and heat transfer fluid containers for heated air conditioning systems.

[0029] After circulating water passes through the cylinder liner water heat exchanger or exits through the cylinder liner water heat exchanger, it must enter the fuel water heating device 6 for heating as long as it has not reached the design temperature.

[0030] The hot water circulation pump set 5 can be operated in 1 to 2 units according to the water flow in the system, and a bypass is set to prevent the water flow from exceeding the set value when one pump is started.

[0031] The working principle of this invention is as follows: The circulating water first undergoes heat exchange in the cylinder liner water heat exchanger. After heat exchange, it enters the cylinder liner water heating collector 11. Valves CHV42 / 37 / 38 are closed, and valve CHV34 is open. The design temperature of the circulating water is 85~88℃, controlled by the temperature control valve CHV3 (i.e., the first temperature control valve). If the design temperature is reached, it flows to the pipeline of valve CHV29 and enters the heating distributor 8. If the design temperature is not reached, it flows to the pipeline of valve CHV32 and enters the fuel oil hot water heating device 6 to be heated to above 85℃. Then, it enters the heating distributor 8 from the pipeline where valve CHV31 is located. The circulating water is distributed from the heating distributor 8 to the heating chamber, seawater desalination, heating electric / hot water tank, and heating air conditioning system heat transfer medium water. After the heat is absorbed, it returns from each user to the heating return collector 9, and then enters the hot water circulating pump group 5 through valve CHV49. After being pressurized by the pump, it enters the heat source return water device 10. After exiting the heat source return water unit 10, the flow direction is controlled by four temperature control valves CHV5 / 6 / 7 / 8 (i.e., the second temperature control valve). If the circulating water temperature still reaches 65~68℃, it will directly enter the cylinder liner water heat supply collector 11 without passing through the cylinder liner water heat exchanger, completing one cycle.

[0032] Depending on the number of main engines operating during ship operation, the opening and closing of control valves CHV21 / 19, CHV11 / 9, CHV12 / 10, and CHV22 / 20 allows selection of whether to activate the four cylinder liner water heat exchangers, thereby controlling the circulating water flow rate. When only one cylinder liner water heat exchanger 1 is activated, if the flow rate of one pump in the hot water circulating pump group 5 (45 m³ / h) exceeds the actual demand, the electric valve CHV2 opens, automatically bypassing the circulating water flow. When 2 to 4 cylinder liner water heat exchangers are activated, 2 pumps in the hot water circulating pump group 5 start, reaching a flow rate of 90 m³ / h, with the remaining circulating pump serving as a standby pump.

[0033] If the cylinder liner water heat exchangers are not required according to operational needs, the circulating water can be bypassed from the heat source return water device 10 through the pipeline where valve CHV48 / 46 is located to the cylinder liner water heating collector 11.

[0034] The system of this invention can change the opening and closing state of valves to control the operation of different parts of the system to adapt to different working conditions. When it is summer or the ship is in a hot area, the user end does not need heating. The phase change heat storage device 7 can be used to store heat. The circulation process is as follows: the circulating water first exchanges heat in the cylinder jacket water heat exchanger. After the heat exchange is completed, it enters the cylinder jacket water heating water collector 11. Valves CHV34 / 37 / 38 / 44 / 41 are closed and valves CHV42 / 43 are open. The design temperature of the circulating water is 85~88℃. The heat will enter the phase change heat storage device 7 for heat storage. The phase change material is hydrated salt (sodium acetate trihydrate). The applicable temperature is 45~90℃. After the heat is absorbed, the circulating water goes to the heating return collector 9, and then enters the hot water circulation pump group 5 through valve CHV49. After being pressurized by the pump, it enters the heat source return water collector 10. After exiting the heat source return water unit 10, the flow direction is controlled by four temperature control valves CHV5 / 6 / 7 / 8. If the circulating water temperature still reaches 65~68℃, it will directly enter the cylinder liner water heat exchanger 11 without passing through the cylinder liner water heat exchanger, completing one cycle. When it is winter or the ship is located in a cold region, valves CHV42 / 44 remain closed, and valve CHV34 is open to deliver heat to each user.

[0035] When the ship's main engine is shut down, and the main engine cylinder liner water heat exchanger is not used or only one cylinder liner water heat exchanger is used, the heat of the circulating water is insufficient. The heat in the phase change accumulator 7 can be used. The circulation process is as follows: valves CHV34 / 42 / 43 are closed, and CHV41 / 44 are opened. The circulating water in the heat storage system flows out from the pipeline where valve CHV41 is located. After being controlled by the temperature control valve CHV4 (i.e., the third temperature control valve), if the design temperature of 85~88℃ is reached, it flows to the pipeline of valve CHV40 and enters the heating distributor 8; if the design temperature is not reached, it flows to the pipeline of valve CHV39 and enters the fuel oil hot water heating device 6. After being heated to a temperature greater than 85℃, it enters the heating distributor 8 from the pipeline where valve CHV31 is located. The circulating water is distributed from the heating distributor 8 to the heating chamber, seawater desalination, heating electric / hot water tank, and heating air conditioning system. After the heat is absorbed, the water returns from each user to the heating collector 9, and then returns to the phase change heat storage unit 7 via the hot water circulation pump 12 of the heat storage system, completing one cycle.

Claims

1. A waste heat recovery system for marine main engines, characterized in that, This includes a hot water circulation system, a fuel-fired hot water heating system, and a thermal storage system. The hot water circulation system includes multiple cylinder-lined water heat exchangers for circulating water heat exchange. The outlet of each cylinder-lined water heat exchanger is connected to the inlet of the cylinder-lined water heating collector (11) through a pipeline. The outlet of the cylinder-lined water heating collector (11) is connected to the inlet of the heating distributor (8) through a pipeline. The outlet of the heating distributor (8) is connected to each user through various pipelines. Each user is connected to the inlet of the heating return collector (9) through a pipeline. The outlet of the heating return collector (9) is connected to the inlet of the hot water circulation pump group (5) through a pipeline. The outlet of the hot water circulation pump group (5) is connected to the inlet of the heat source return water device (10) through a pipeline. The outlet of the heat source return water device (10) is connected to the inlet of each cylinder-lined water heat exchanger through a pipeline. The fuel-fired hot water heating system includes a fuel-fired hot water heating device (6), the outlet of the cylinder liner water heating collector (11) is connected to the inlet of the fuel-fired hot water heating device (6) through a pipeline, and the outlet of the fuel-fired hot water heating device (6) is connected to the inlet of the heating distributor (8) through a pipeline. The heat storage system includes a phase change heat storage device (7). The outlet of the cylinder liner water heating collector (11) is connected to the inlet of the phase change heat storage device (7) through a pipeline. The outlet of the phase change heat storage device (7) is connected to the inlet of the heat return collector (9), the inlet of the fuel oil hot water heating device (6), and the inlet of the heat distributor (8) through pipelines. The outlet of the heat return collector (9) is connected to the inlet of the phase change heat storage device (7) through a pipeline with a heat storage system hot water circulation pump (12). Each pipeline is equipped with a valve.

2. The waste heat recovery system for a ship's main engine as described in claim 1, characterized in that, The outlet of the cylinder liner water heating collector (11) is divided into two paths. One path leads to the fuel oil hot water heating device (6) and the heating distributor (8), and the other path leads to the inlet of the phase change heat accumulator (7). The path leading to the fuel oil hot water heating device (6) and the heating distributor (8) is equipped with a first temperature control valve. After passing through the first temperature control valve, it is divided into two paths. One path leads to the inlet of the fuel oil hot water heating device (6), and the other path leads to the inlet of the heating distributor (8).

3. The waste heat recovery system for a ship's main engine as described in claim 1, characterized in that, The outlet of the heat source return water device (10) is divided into two types. One type is connected to the inlet of the cylinder liner water heating collector (11) through a pipeline. The other type has a second temperature control valve installed on each pipeline leading to the cylinder liner water heat exchanger. After passing through the second temperature control valve, the pipeline is divided into two paths: one path leads to the inlet of the cylinder liner water heat exchanger, and the other path leads to the inlet of the cylinder liner water heating return collector (11).

4. The waste heat recovery system for a ship's main engine as described in claim 1, characterized in that, The hot water circulation pump set (5) includes three pumps connected in parallel, two of which are in use and one is in standby. Each pump is equipped with a valve on its pipeline. The inlet and outlet ends of the hot water circulation pump set (5) are equipped with a bypass pipeline with a valve.

5. A marine main engine waste heat recovery system as described in claim 1, characterized in that, The phase change heat storage device (7) has two outlets. One outlet leads to the fuel oil hot water heating device (6) and the heat distribution device (8), and the other outlet leads to the heat collection device (9). A third temperature control valve is provided on the outlet leading to the fuel oil hot water heating device (6) and the heat distribution device (8). After passing through the third temperature control valve, the outlet is divided into two outlets. One outlet leads to the inlet of the fuel oil hot water heating device (6), and the other outlet leads to the inlet of the heat distribution device (8).

6. The marine main engine waste heat recovery system as described in claim 1, characterized in that, The users mentioned include heated chambers, seawater desalination plants, heated electric / hot water tanks, and heat transfer water containers for heated air conditioning systems.

7. A method for recovering waste heat from a ship's main engine, characterized in that, Using a marine main engine waste heat recovery system as described in any one of claims 1-6, when the ship is in winter or in a cold region, the system includes the following steps: Circulating water first undergoes heat exchange in the cylinder liner water heat exchanger. After heat exchange, it enters the cylinder liner water heating collector (11) and then enters the first temperature control valve for temperature measurement. If the circulating water temperature reaches the design temperature of the first temperature control valve, the circulating water flows to and enters the heating distributor (8). If the circulating water temperature does not reach the design temperature of the first temperature control valve, the circulating water flows to and enters the fuel oil hot water heating device (6). When the circulating water is heated by the fuel oil hot water heating device (6) to a temperature greater than the maximum design temperature of the first temperature control valve... After the temperature is measured, the circulating water enters the heating distributor (8) through the pipeline from the outlet of the fuel water heating device (6). The circulating water is distributed to each user through the heating distributor (8). After the heat is absorbed, the water returns from each user to the heating collector (9) and then enters the hot water circulation pump group (5). After being pressurized by the pump of the hot water circulation pump group (5), it enters the heat source return water device (10). After coming out of the heat source return water device (10), it flows to the second temperature control valve corresponding to each cylinder liner water heat exchanger. If the circulating water temperature still reaches the design temperature of the second temperature control valve, it does not pass through the cylinder liner water heat exchanger and directly enters the cylinder liner water heating collector (11) to complete one cycle.

8. A method for recovering waste heat from a ship's main engine as described in claim 7, characterized in that, When it is summer or the ship is in a hot region, the users do not need to heat the water. They use the phase change heat storage device (7) to store heat. The circulation process is as follows: the circulating water first exchanges heat in the cylinder liner water heat exchanger. After the heat exchange is completed, it enters the cylinder liner water heating collector (11) and then enters the phase change heat storage device (7) to store heat. After the heat is absorbed, the circulating water goes to the heating return collector (9) and then enters the hot water circulation pump group (5). After being pressurized by the pump, it enters the heat source return water device (10). After coming out of the heat source return water device (10), the flow direction is controlled by the second temperature control valve. If the circulating water temperature still reaches the design temperature of the second temperature control valve, it will directly enter the cylinder liner water heating return collector (11) without going through the cylinder liner water heat exchanger, thus completing one cycle.

9. A method for recovering waste heat from a ship's main engine as described in claim 8, characterized in that, When the ship's main engine is shut down, if the cylinder liner water heat exchanger is not used or only one cylinder liner water heat exchanger is used, the heat of the circulating water is insufficient. The heat in the phase change accumulator (7) is used. The circulation process is as follows: the circulating water of the phase change accumulator (7) is controlled by the third temperature control valve. If the design temperature of the third temperature control valve is reached, it enters the heating distributor (8); if the design temperature of the third temperature control valve is not reached, it enters the fuel oil hot water heating device (6). When the circulating water is heated by the fuel oil hot water heating device (6) to a temperature greater than the maximum design temperature of the third temperature control valve, it enters the heating distributor (8). The circulating water is distributed from the heating distributor (8) to each user. After the heat is absorbed, the water returns from each user to the heating return collector (9) and returns to the phase change accumulator (7) through the hot water circulation pump (12) of the heat storage system, completing one cycle.

10. A method for recovering waste heat from a ship's main engine as described in claim 9, characterized in that, The circulating water temperature designed for the first temperature control valve position is 85~88℃; the circulating water temperature designed for the second temperature control valve position is 65~68℃; and the circulating water temperature designed for the third temperature control valve position is 85~88℃.

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